This invention relates to a concurrent processing controlling method and apparatus for computer programs on a B.sup.+ tree structure. There are various memorizing methods for data in processing the computer program, such as Hash, B tree. Lehamn P. L. and Yao S. B. "Efficient Locking for Concurrent Operation on B-trees" ACM TODS 6.4 (December 1981) pp 650-670 describes a concurrent processing control system on a B.sup.+ tree structure having transverse links on all nodes. This conventional control system, however, can not expand to the dual-direction links. Also, Mond Y and Raz Y. "Concurrency Control in B.sup.+ -trees Database using Preparatory Operation" Proc. of VLDB 85, (1985) pp 331-334 describes a control method carried on deforming B.sup.+ tree, in which individual controls are independently done on the leaf portions and the other portions. There is another product of VSAM (IBM) using an algorithm similar to that above. The product has a demerit that links are only uni-directional type and that the whole volume of the tree structure is not decreased after deleting.
As mentioned above, according to the prior art, it has only the kind of uni-directional links, and the control on leaf portions and the other portions are done separately.